The Veterinary Resources Program, National Center for Research Resources, has established a Watanabe heritable hyperlipidemic (WHHL) rabbit breeding colony as a resource for investigators requiring this animal model for use in human familial hypercholesterolemia due to a low density lipoprotein receptor defect. The purpose of this project is to characterize the serum cholesterol and triglyceride values of the NIH WHHL rabbit colony. Blood was collected from WHHL rabbits at eight weeks, three months, seven months, and twelve months of age. The serums were analyzed for lipoprotein cholesterol and triglycerides. A computer program has been developed to track pedigrees of the WHHL rabbits, making it possible to evaluate the influence of genotype on cholesterol and triglyceride values. Total serum cholesterol values range from 310 to 1251 mg/dl with a mean of 828 mg/dl. The low density lipoprotein (LDL) cholesterol values range from 70 to 1185 mg/dl with a mean of 630 mg/dl. Serum triglyceride values range from 107 to 959 mg/dl with a mean of 394 mg/dl. There appears to be a correlation between serum triglyceride concentration and the sex of the rabbit. The mean male and female triglyceride concentrations were 510 mg/dl and 309 mg/dl, respectively.